In a damper device which is used in a cold air passage of a refrigerator or the like, a structure has been proposed in which a baffle is turnably driven by, for example, a drive mechanism including a stepping motor and a gear train to open and close an opening part formed in a frame (see Patent Literature 1). Further, in the damper device described in Patent Literature 1, a lock mechanism for maintaining a posture of the baffle is provided between a drive gear and a sector gear used in the gear train. In the lock mechanism, a circular arc-shaped outer peripheral part of the drive gear is entered to portions whose dimensions in an axial line direction are narrowed of a second and a third teeth from one end in a circumferential direction in a plurality of the teeth of the sector gear and thereby the sector gear is restricted.